Pheochromocytomas: imaging with 2-[fluorine-18]fluoro-2-deoxy-D-glucose PET

Image-Guided Precision Medicine in the Diagnosis and Treatment of Pheochromocytomas and Paragangliomas

In this comprehensive review, we aimed to discuss the current state-of-the-art medical imaging for pheochromocytomas and paragangliomas (PPGLs) diagnosis and treatment. Despite major medical improvements, PPGLs, as with other neuroendocrine tumors (NETs), leave clinicians facing several challenges; their inherent particularities and their diagnosis and treatment pose several challenges for clinicians due to their inherent complexity, and they require management by multidisciplinary teams. The conventional concepts of medical imaging are currently undergoing a paradigm shift, thanks to developments in radiomic and metabolic imaging. However, despite active research, clinical relevance of these new parameters remains unclear, and further multicentric studies are needed in order to validate and increase widespread use and integration in clinical routine. Use of AI in PPGLs may detect changes in tumor phenotype that precede classical medical imaging biomarkers, such as shape, texture, and size. Since PPGLs are rare, slow-growing, and heterogeneous, multicentric collaboration will be necessary to have enough data in order to develop new PPGL biomarkers. In this nonsystematic review, our aim is to present an exhaustive pedagogical tool based on real-world cases, dedicated to physicians dealing with PPGLs, augmented by perspectives of artificial intelligence and big data.

A Comprehensive Review on Neuroendocrine Neoplasms: Presentation, Pathophysiology and Management

Neuroendocrine neoplasms (NENs) are a group of heterogeneous tumors with neuroendocrine differentiation that can arise from any organ. They account for 2% of all malignancies in the United States. A significant proportion of NEN patients experience endocrine imbalances consequent to increased amine or peptide hormone secretion, impacting their quality of life and prognosis. Over the last decade, pathologic categorization, diagnostic techniques and therapeutic choices for NENs-both well-differentiated neuroendocrine tumors (NETs) and poorly differentiated neuroendocrine carcinomas (NECs)-have appreciably evolved. Diagnosis of NEN mostly follows a suspicion from clinical features or incidental imaging findings. Hormonal or non-hormonal biomarkers (like serum serotonin, urine 5-HIAA, gastrin and VIP) and histology of a suspected NEN is, therefore, critical for both confirmation of the diagnosis and classification as an NET or NEC. Therapy for NENs has progressed recently based on a better molecular understanding, including the involvement of mTOR, VEGF and peptide receptor radionuclide therapy (PRRT), which add to the growing evidence supporting the possibility of treatment beyond complete resection. As the incidence of NENs is on the rise in the United States and several other countries, physicians are more likely to see these cases, and their better understanding may support earlier diagnosis and tailoring treatment to the patient. We have compiled clinically significant evidence for NENs, including relevant changes to clinical practice that have greatly updated our diagnostic and therapeutic approach for NEN patients.

Metastatic pheochromocytoma and paraganglioma: a retrospective multicentre analysis on prognostic and predictive factors to chemotherapy

Background

Prognostic and predictive markers in metastatic pheochromocytoma and paraganglioma (mPPGL) are unknown. We aimed to evaluate epidemiology of mPPGL, and prognostic factors of overall survival (OS) and predictive markers of treatment duration with first-line chemotherapy (TD1L).

Patients and methods

Retrospective multicentre study of adult patients with mPPGL treated in Latin American centres between 1982 and 2021.

Results

Fifty-eight patients were included: 53.4% were female, median age at diagnosis of mPPGL was 36 years and 12.1% had a family history of PPGL. The primary site was adrenal, non-adrenal infradiaphragmatic and supradiaphragmatic in 37.9%, 34.5% and 27.6%, respectively. 65.5% had a functioning tumour and 62.1% had metachronous metastases. Positive uptakes were found in 32 (55.2%) ⁶⁸Gallium positron emission tomography (PET/CT), 27 (46.6%) 2-deoxy-2-[fluorine-18]fluoro-D-glucose PET/CT and 37 (63.8%) of ¹³¹Iodine-metaiodobenzylguanidine (MIBG) tests. Twenty-three (40%) patients received first-line chemotherapy, with cyclophosphamide, vincristine and dacarbazine used in 12 (52%) of patients. At a median follow-up of 62.8 months, median TD1L was 12.8 months. Either functional exams, tumour functionality, pathological characteristics or primary tumour location were significantly associated with response or survival. Yet, negative MIBG, Ki67 ≥ 10%, infradiaphragmatic location and functional tumours were associated with numerically inferior OS.

Conclusions

In patients with mPPGL, prognostic and predictive factors to chemotherapy are still unknown, but negative MIBG uptake, Ki67 ≥ 10%, infradiaphragmatic location and functional tumours were numerically linked to worse OS. Our results should be further validated in larger and independent cohorts.

Adrenal Lesions: A Review of Imaging

Adrenal lesions are frequently incidentally diagnosed during investigations for other clinical conditions. Despite being usually benign, nonfunctioning, and silent, they can occasionally cause discomfort or be responsible for various clinical conditions due to hormonal dysregulation; therefore, their characterization is of paramount importance for establishing the best therapeutic strategy. Imaging techniques such as ultrasound, computed tomography, magnetic resonance, and PET-TC, providing anatomical and functional information, play a central role in the diagnostic workup, allowing clinicians and surgeons to choose the optimal lesion management. This review aims at providing an overview of the most encountered adrenal lesions, both benign and malignant, including describing their imaging characteristics.

An Appraisal and Update of Fluorodeoxyglucose and Non-Fluorodeoxyglucose-PET Tracers in Thyroid and Non-Thyroid Endocrine Neoplasms

Endocrine neoplasms and malignancies are a diverse group of tumors with varied clinical, histopathologic, and functional features. These tumors vary from sporadic to hereditary, isolated entities to multiple neoplastic syndromes, functioning and non functioning tumors, unifocal locally invasive, and advanced to multifocal tumors with disseminated distant metastases. The presence of various specific biomarkers and specific receptor targets serves as valuable tools for diagnosis, prognosis, and management. PET-CT with FDG and a multitude of novel and specific radiotracers towards specific therapeutic targets mandates personalization of their use, so as to ensure maximum clinical benefit in the management of these neoplasms.

Imaging of Pheochromocytoma and Paraganglioma

Imaging plays a critical role in the management of pheochromocytomas and paragangliomas and often guides treatment. The discovery of susceptibility genes associated with these tumors has led to better understanding of clinical and imaging phenotypes. Functional imaging is of prime importance because of its sensitivity and specificity in subtypes of pheochromocytoma and paraganglioma. Several radiopharmaceuticals have been developed to target specific receptors and metabolic processes seen in pheochromocytomas and paragangliomas, including 131I/123I-metaiodobenzylguanidine, 6-18F-fluoro-l-3,4-dihydroxyphenylalanine, 18F-FDG, and 68Ga-DOTA-somatostatin analogs. Two of these have consequently been adapted for therapy. This educational review focuses on the current imaging approaches used in pheochromocytomas and paragangliomas, which vary among clinical and genotypic presentations.

Open versus minimally invasive surgery for suspected adrenocortical carcinoma

Adrenocortical carcinoma (ACC) is a rare malignancy with a poor prognosis. Although laparoscopy has been widely adopted for management of benign adrenal tumors, minimally invasive surgery for ACC remains controversial. Retrospective analyses, frequently with fewer than one hundred participants, comprise the majority of the literature. High-quality data regarding the optimal surgical approach for ACC are lacking due to the rarity of the disease and the fact that determination of tumor type (e.g., adenoma or carcinoma) is determined after adrenalectomy, since adrenal tumors are generally not biopsied. While the benefits of minimally invasive surgery including lower intra-operative blood loss and decreased hospital length-of-stay have been consistently demonstrated, clinical equipoise for long-term survival and recurrence outcomes between open and minimally invasive adrenalectomy (MIA) remains. This review examines retrospective studies that directly compare patients with ACC who underwent either open or laparoscopic adrenalectomy, and considers these findings in the context of current guideline recommendations for surgical management of ACC.

Pheochromocytoma: A three-decade clinical experience in a multicenter study

OBJECTIVE

To analyze the clinical and analytical features, diagnostic tests, therapies, and outcomes of pheochromocytoma (PCC).

DESIGN AND METHODS

A multicenter retrospective study in surgically treated patients with PCC followed in 3 Spanish tertiary referral hospitals.

RESULTS

A total of 106 patients (61 [57.5%] women, mean age 52.3 ± 14.8 years) were evaluated. At diagnosis, PCC was symptomatic in 62% and sporadic in 83%. Patients with familial PCC were significantly younger than those with sporadic disease (40.8 ± 14.2 years vs. 54.5 ± 13.9 years, p<.001). Familial PCCs were more frequently associated with MEN2A (n=8). Levels of 24-h urinary fractionated metanephrines were positively related to tumor size. The maximum tumor diameter was 4.3cm (3-6cm); 27.7% of the patients had tumors ≥6cm. Incidental PCCs were significantly smaller than symptomatic PCCs (3.4cm [2.4-5.0cm] vs. 5.6cm [4.0-7.0cm], p<.001). Scintigraphy by 123I-metaiodobenzylguanidine showed a high sensitivity (81.9%). Preoperative alpha blockade with phenoxybenzamine was used in 93.6% and doxazosin in the rest. Laparoscopic surgery was used in 2/3 of the patients, with a low conversion (1.9%) to open surgery. Perioperative complications appeared in approximately 20% of patients, mainly hypertensive crisis (9.4%). Recurrent disease appeared in 10%, and malignant PCC was uncommon (6.3%).

CONCLUSIONS

PCCs surgically treated in Spain are usually large, symptomatic, and sporadic tumors diagnosed around the sixth decade of life. Hereditary PCC is usually associated with MEN2A. The main type of surgical technique used is laparoscopic surgery, and the prevalence of metastatic PCC is low.

Pheochromocytoma: A three-decade clinical experience in a multicenter study

OBJECTIVE

To analyze the clinical and analytical features, diagnostic tests, therapies, and outcomes of pheochromocytoma (PCC).

DESIGN AND METHODS

A multicenter retrospective study in surgically treated patients with PCC followed in 3 Spanish tertiary referral hospitals.

RESULTS

A total of 106 patients (61 [57.5%] women, mean age 52.3 ± 14.8 years) were evaluated. At diagnosis, PCC was symptomatic in 62% and sporadic in 83%. Patients with familial PCC were significantly younger than those with sporadic disease (40.8 ± 14.2 years vs 54.5 ± 13.9 years, p < .001). Familial PCCs were more frequently associated with MEN2A (n = 8). Levels of 24-h urinary fractionated metanephrines were positively related to tumor size. The maximum tumor diameter was 4.3 cm (3-6 cm); 27.7% of the patients had tumors ≥6 cm. Incidental PCCs were significantly smaller than symptomatic PCCs (3.4 cm [2.4-5.0 cm] vs 5.6 cm [4.0-7.0 cm], p < .001). Scintigraphy by ¹²³I-metaiodobenzylguanidine showed a high sensitivity (81.9%). Preoperative alpha blockade with phenoxybenzamine was used in 93.6% and doxazosin in the rest. Laparoscopic surgery was used in 2/3 of the patients, with a low conversion (1.9%) to open surgery. Perioperative complications appeared in approximately 20% of patients, mainly hypertensive crisis (9.4%). Recurrent disease appeared in 10%, and malignant PCC was uncommon (6.3%).

CONCLUSIONS

PCCs surgically treated in Spain are usually large, symptomatic, and sporadic tumors diagnosed around the sixth decade of life. Hereditary PCC is usually associated with MEN2A. The main type of surgical technique used is laparoscopic surgery, and the prevalence of metastatic PCC is low.

The value of multiparameter 18F-FDG PET/CT imaging in differentiating retroperitoneal paragangliomas from unicentric Castleman disease

The aim of this study was to investigate the value of multiple parameters retrieved from the FDG PET/CT studies, including SUVmax, SUVmean, SUVpeak, MTV, TLG, tumour size in differentiating retroperitoneal paragangliomas from UCD. 28 patients with solitary retroperitoneal masses who had undergone preoperative 18F-FDG PET/CT were retrospectively evaluated. Histopathology by surgical resection confirmed 17 paragangliomas and 11 UCDs. SUVmax, SUVmean, SUVpeak, MTV, TLG, and tumour size of 18F-FDG PET/CT were measured for each patient. Mann-Whitney U-test was used to assess differences in multiple parameters between paragangliomas and UCDs. The ROC curve analysis was performed to determine the differential diagnostic value of these parameters. Paragangliomas presented significantly higher SUVmax (P < 0.001), SUVmean (P = 0.001), SUVpeak (P < 0.001), and TLG (P = 0.024) than UCDs, whereas no significant difference was observed in MTV. The AUCs for differentiating paragangliomas and UCDs were 0.920, 0.888, 0.909, and 0.765 for SUVmax, SUVmean, SUVpeak, and TLG, respectively. The SUVmax cut-off of 7.75 yielded 82.4% sensitivity and 100% specificity for predicting paragangliomas. This study indicated that 18F FDG PET/CT-derived multiple metabolic parameters are useful in distinguishing between paragangliomas and UCDs. SUVmax showed the best result for the differential diagnosis of these two diseases among multiple metabolic parameters.

Diagnostic efficacy of 18F-FDG PET/CT in patients with adrenal incidentaloma

BACKGROUND

The management of adrenal incidentaloma is still a challenge with respect to determining its functionality (hormone secretion) and malignancy. In this light, we performed 18F-FDG PET/CT scan to assess the SUVmax values in different adrenal masses including Cushing syndrome, pheochromocytoma, primary hyperaldosteronism and non-functional adrenal adenomas.

METHODS

Total 109 (73 F, 36 M) patients with adrenal mass (incidentaloma), mean age of 53.3 ± 10.2 years (range, 24-70) were screened by 18F-FDG PET/CT. Data of 18F-FDG PET/CT imaging of the patients were assessed by the same specialist. Adrenal masses were identified according to the calculated standardized uptake values (SUVs). Clinical examination, 24-h urine cortisol, catecholamine metabolites, 1-mg dexamethasone suppression test, aldosterone/renin ratio and serum electrolytes were analyzed.

RESULTS

Based on the clinical and hormonal evaluations, there were 100 patients with non-functional adrenal mass, four with cortisol-secreting, four with pheochromocytomas and one with aldosterone-secreting adenoma. Mean adrenal mass diameter of 109 patients was 2.1 ± 4.3 (range, 1-6.5 cm). The 18F-FDG PET/CT imaging of the patients revealed that lower SUVmax values were found in non-functional adrenal masses (SUVmax 3.2) when compared to the functional adrenal masses including four with cortisol-secreting adenoma (SUVmax 10.1); four with pheochromcytoma (SUVmax 8.7) and one with aldosterone-secreting adenomas (SUVmax 3.30). Cortisol-secreting (Cushing syndrome) adrenal masses showed the highest SUVmax value (10.1), and a cut-off SUVmax of 4.135 was found with an 84.6% sensitivity and 75.6% specificity cortisol-secreting adrenal adenoma.

CONCLUSIONS

Consistent with the similar studies, non-functional adrenal adenomas typically do not show increased FDG uptake and a certain form of functional adenoma could present various FDG uptake in FDG PET/CT. Especially functional adrenal adenomas (cortisol secreting was the highest) showed increased FDG uptake in comparison to the non-functional adrenal masses. Therefore, setting a specific SUVmax value in the differentiation of malignant adrenal lesion from the benign one is risky and further studies, including a high number of functional adrenal mass are needed.

11C-hydroxy-ephedrine-PET/CT in the Diagnosis of Pheochromocytoma and Paraganglioma

Pheochromocytomas (PCC) and paragangliomas (PGL) may be difficult to diagnose because of vague and uncharacteristic symptoms and equivocal biochemical and radiological findings. This was a retrospective cohort study in 102 patients undergoing ¹¹C-hydroxy-ephedrine (¹¹C-HED)-PET/CT because of symptoms and/or biochemistry suspicious for PCC/PGL and/or with radiologically equivocal adrenal incidentalomas. Correlations utilized CT/MRI, clinical, biochemical, surgical, histopathological and follow-up data. ¹¹C-HED-PET/CT correctly identified 19 patients with PCC and six with PGL, missed one PCC, attained one false positive result (nodular hyperplasia) and correctly excluded PCC/PGL in 75 patients. Sensitivity, specificity, positive and negative predictive values of ¹¹C-HED-PET/CT for PCC/PGL diagnosis was 96%, 99%, 96% and 99%, respectively. In 41 patients who underwent surgical resection and for whom correlation to histopathology was available, the corresponding figures were 96%, 93%, 96% and 93%, respectively. Tumor ¹¹C-HED-uptake measurements (standardized uptake value, tumor-to-normal-adrenal ratio) were unrelated to symptoms of catecholamine excess (p > 0.05) and to systolic blood pressure (p > 0.05). In PCC/PGL patients, norepinephrine and systolic blood pressure increased in parallel (R² = 0.22, p = 0.016). ¹¹C-HED-PET/CT was found to be an accurate tool to diagnose and rule out PCC/PGL in complex clinical scenarios and for the characterization of equivocal adrenal incidentalomas. PET measurements of tumor ¹¹C-HED uptake were not helpful for tumor characterization.

Surgical therapy of adrenal tumors: guidelines from the German Association of Endocrine Surgeons (CAEK)

BACKGROUND AND AIMS

Previous guidelines addressing surgery of adrenal tumors required actualization in adaption of developments in the area. The present guideline aims to provide practical and qualified recommendations on an evidence-based level reviewing the prevalent literature for the surgical therapy of adrenal tumors referring to patients of all age groups in operative medicine who require adrenal surgery. It primarily addresses general and visceral surgeons but offers information for all medical doctors related to conservative, ambulatory or inpatient care, rehabilitation, and general practice as well as pediatrics. It extends to interested patients to improve the knowledge and participation in the decision-making process regarding indications and methods of management of adrenal tumors. Furthermore, it provides effective medical options for the surgical treatment of adrenal lesions and balances positive and negative effects. Specific clinical questions addressed refer to indication, diagnostic procedures, effective therapeutic alternatives to surgery, type and extent of surgery, and postoperative management and follow-up regime.

METHODS

A PubMed research using specific key words identified literature to be considered and was evaluated for evidence previous to a formal Delphi decision process that finalized consented recommendations in a multidisciplinary setting.

RESULTS

Overall, 12 general and 52 specific recommendations regarding surgery for adrenal tumors were generated and complementary comments provided.

CONCLUSION

Effective and balanced medical options for the surgical treatment of adrenal tumors are provided on evidence-base. Specific clinical questions regarding indication, diagnostic procedures, alternatives to and type as well as extent of surgery for adrenal tumors including postoperative management are addressed.

Quantitative analysis of normal and pathologic adrenal glands with 18F-FDOPA PET/CT: focus on pheochromocytomas

INTRODUCTION

Many studies have reported the high performance of 6-fluorine-18-fluorodihydroxyphenilalanine (F-FDOPA) PET/CT in the diagnosis of pheochromocytomas but nobody seems to have investigated physiological and pathological adrenal glands from a quantitative point of view. The purpose of the present study was to assess the quantitative F-FDOPA uptake of normal and pathologic adrenal glands and to establish thresholds to characterize pheochromocytomas. We were especially interested in characterizing the remaining adrenal glands captation after an adrenalectomy.

PATIENTS AND METHODS

We reviewed 112 F-FDOPA PET/CT scans taken for different indications. A total of 212 adrenal glands, of which 17 were pheochromocytomas, were analyzed on the basis of their functional and morphological features. The final diagnosis was based on histologic proof when available (six pheochromocytomas) or after synthesis of clinical, biological, morphological, and functional results. Maximum standardized uptake value (SUVmax), mediastinum, and liver ratios in case of pheochromocytomas, adenomas, and solitary adrenal glands were determined and compared with those of healthy glands. Receiver operating characteristic curves were determined and areas under the curve were compared for different cutoffs of each index.

RESULTS

Pheochromocytomas demonstrated a higher F-FDOPA uptake compared with normal adrenal glands (mean SUVmax: 7.5, SD 4.0, range: 3.5-20.0 vs. mean SUVmax: 2.6, SD: 0.8, range: 1.0-6.9) (P<0.0001). An SUVmax threshold of 4.2 has a sensitivity and specificity of 94 and 98%, respectively. The areas under the curve were 0.988, 0.991, and 0.987 for an SUVmax of 4.2, a mediastinum ratio of 3.0, and a liver ratio of 1.7, respectively. A large number of nonsecreting pheochromocytomas were noticed. On the basis of the SUVmax no statistically significant difference was found between secreting (SUVmax: 8.9, SD: 5.3) and nonsecreting pheochromocytomas (SUVmax: 5.1, SD: 0.9) (P=0.141). After unilateral adrenalectomy, solitary glands presented no increased uptake compared with healthy adrenal glands. An unexpected lower captation was also observed (SUVmax: 2.0, P=0.047).

CONCLUSION

We confirm the high affinity of F-FDOPA for secreting or nonsecreting pheochromocytoma. Indeed within a series of various adrenal glands, only these tumors presented a significant increased uptake compared with normal adrenal glands. Because of a high rate of nonhypersecreting lesions, F-FDOPA can act as a surrogate to biological assays. After an adrenalectomy, the remaining glands did not demonstrate compensatory accumulation of F-FDOPA. To our knowledge this last point has never been addressed.

PET-CT and PET-MR in urological cancers other than prostate cancer: An update on state of the art

Hybrid positron emission tomography with computed tomography (PET/CT) and magnetic resonance imaging (PET/MRI) have enabled the combination of morphologic and functional imaging with the promise of providing better information in guiding therapy. Further advance has been made in the past decade with the development of newer radiotracers and optimization of the technical aspects. We performed a search in PubMed, Scopus, and Google Scholar for peer-reviewed literature concerning the advances and newer developments in the imaging of nonprostate urologic cancers between 2005 and 2017. This review aims at summarizing the current evidence on PET imaging in nonprostate urologic cancers and their impact on the diagnosis, staging, prognostication, response assessment, and restaging of these malignancies. However, much of the evidence is still in infancy and has not been incorporated into routine management or the practice guidelines of National Comprehensive Cancer Network or European Society for Medical Oncology (ESMO).

Texture analysis of FDG PET/CT for differentiating between FDG-avid benign and metastatic adrenal tumors: efficacy of combining SUV and texture parameters

PURPOSE

To retrospectively investigate the SUV-related and texture parameters individually and in combination for differentiating between F-18-fluorodeoxyglucose (FDG)-avid benign and metastatic adrenal tumors with PET/CT.

METHODS

Thirteen benign adrenal tumors (BATs) and 22 metastatic adrenal tumors (MATs) with a metabolic tumor volume (MTV) > 10.0 cm³ and SUV ≥ 2.5 were included. SUVmax, MTV, total lesion glycolysis, and four textural parameters [entropy, homogeneity, intensity variability (IV), and size-zone variability] were obtained. These parameters were compared between BATs and MATs using Mann-Whitney U test, and the diagnostic performance was evaluated by the area under the curve (AUC) values derived from the receiver operating characteristic analysis. The diagnostic value of combining SUV and texture parameters was examined using a scoring system.

RESULTS

MATs showed significantly higher SUV_max (p = 0.004), entropy (p = 0.013), IV (p = 0.006), and lower homogeneity (p = 0.019) than BATs. The accuracies for diagnosing MATs were 82.9, 82.9, 85.7, and 71.4% for SUV_max, entropy, IV, and homogeneity, respectively. No significant differences in AUC were found among these parameters (p > 0.05 each). When each parameter was scored as 0 (negative for malignancy) and 1 (positive for malignancy) according to each threshold criterion and the four parameter summed scores 0, 1, and 2 were defined as benignity and 3 and 4 as malignancy, the sensitivity and specificity and accuracy to predict MATs were 100% (22/22), 84.6% (11/13), and 94.3% (33/35), respectively, with 0.97 of the AUC.

CONCLUSION

The combined use of SUV_max and texture parameters has a potential to significantly increase the diagnostic performance to differentiate between large FDG-avid BATs and MATs.

Adrenal Imaging

Cross-sectional imaging can make a specific diagnosis in lesions, such as myelolipomas, cysts, and hemorrhage, and is often sufficient to distinguish benign from malignant adrenal processes. CT and MRI are useful studies to identify pheochromocytomas and cortisol-secreting or androgen-secreting tumors. In patients with primary aldosteronism, adrenal venous sampling remains the most accurate localizing study and should be performed in all patients older than 35. Radiolabeled isotope studies serve as second-line diagnostic tests for malignant adrenal tumors, primary or metastatic, as well as for pheochromocytoma. Nuclear imaging studies should follow a robust hormonal diagnosis and be correlated with findings on cross-sectional imaging.

Fluorine-18-fluorodihydroxyphenylalanine Positron-emission Tomography Scans of Neuroendocrine Tumors (Carcinoids and Pheochromocytomas)

Objectives:

Conventional methods of imaging neuroendocrine tumors with computed tomography, magnetic resonance imaging, indium-111-octreotide, or radiolabeled metaiodobenzilguanidine scintigraphy have limitations. This pilot study tried to improve the localization of these tumors with fluorine-18-fluorodihydroxyphenylalanine (F-DOPA) positron-emission tomography (PET) scanning.

Materials and Methods:

We studied 22 patients, the majority of whom were referred with clinical diagnosis or suspicion of carcinoid (n = 11), neuroendocrine tumors (n = 7) or pheochromocytoma/paraganglioma (PGL) (n = 4). The comparison was made with the prior conventional imaging.

Results:

The F-DOPA findings were compared with the results of subsequent surgery (2), endoscopy (1), or a long-term follow-up (mean duration, 49 months) for 17 patients. Two patients were lost to follow-up. Foci of F-DOPA deposition were detected in eight patients (final diagnosis of carcinoid in six, of neuroendocrine tumors in one, and of PGL in another). Comparison with the final diagnoses revealed concordance in 16 of the 22 patients. F-DOPA results appeared superior to those obtained with conventional imaging. Despite the small number and diagnostic heterogeneity, in a substantial fraction of patients F-DOPA PET added information relevant to clinical management.

Conclusion:

F-DOPA scanning added prognostic value, particularly when multiple abnormal foci versus a negative examination were considered.

Comparative evaluation of iodine-131 metaiodobenzylguanidine and 18-fluorodeoxyglucose positron emission tomography in assessing neural crest tumors: Will they play a complementary role?

Background:

18-Fluorodeoxyglucose positron emission tomography (FDG-PET) has established a role in the evaluation of several malignancies. However, its precise clinical role in the neural crest cell tumors continues to evolve.

Purpose:

The purpose of this study was to compare iodine-131 metaiodobenzylguanidine (¹³¹I-MIBG) and FDG-PET of head to head in patients with neural crest tumors both qualitatively and semiquantitatively and to determine their clinical utility in disease status evaluation and further management.

Materials and Methods:

A total of 32 patients who had undergone ¹³¹I-MIBG and FDG-PET prospectively were evaluated and clinicopathologically grouped into three categories: neuroblastoma, pheochromocytoma, and medullary carcinoma thyroid.

Results:

In 18 patients of neuroblastoma, FDG PET and ¹³¹I-MIBG showed patient-specific sensitivity of 84% and 72%, respectively. The mean maximum standardized uptake value (SUV_max) of primary lesions in patients with unfavorable histology was found to be relatively higher than those with favorable histology (5.18 ± 2.38 vs. 3.21 ± 1.69). The mean SUV_maxof two common sites (posterior superior iliac spine [PSIS] and greater trochanter) was higher in patients with involved marrow than those with uninvolved one (2.36 and 2.75 vs. 1.26 and 1.34, respectively). The ratio of SUV_maxof the involved/contralateral normal sites was 2.16 ± 1.9. In equivocal bone marrow results, the uptake pattern with SUV estimation can depict metastatic involvement and help in redirecting the biopsy site. Among seven patients of pheochromocytoma, FDG-PET revealed 100% patient-specific sensitivity. FDG-PET detected more metastatic foci than ¹³¹I-MIBG (18 vs. 13 sites). In seven patients of medullary carcinoma thyroid, FDG-PET localized residual, recurrent, or metastatic disease with much higher sensitivity (32 metastatic foci with 72% patient specific sensitivity) than ¹³¹I-MIBG, trending along the higher serum calcitonin levels.

Conclusions:

FDG-PET is not only a good complementary modality in the management of neural crest cell tumors but also it can even be superior, especially in cases of ¹³¹I-MIBG nonavid tumors.

A phantom study: Should 124 I-mIBG PET/CT replace 123 I-mIBG SPECT/CT?

PURPOSE

The isotope ¹²³ I is commonly labeled with meta-iodobenzylguanidine (mIBG) for imaging of neuroendocrine tumors, such as pheochromocytomas and neuroblastomas. ¹²³ I-mIBG SPECT/CT imaging is performed for staging, follow-up and selection of patients for treatment with ¹³¹ I mIBG. As an alternative to ¹²³ I, ¹²⁴ I-mIBG PET/CT may be used, potentially taking advantage of the superior PET image quality. The purpose of this study was to investigate whether ¹²⁴ I PET/CT improves image quality as compared with ¹²³ I SPECT/CT for equal patient effective radiation dose (in mSv).

METHODS

Phantom measurements were performed using the NEMA-2007 image quality phantom. SPECT and PET reconstruction settings were used with and without time-of-flight (TOF) and point-spread-function (PSF) modeling. As a measure of image quality, the contrast-to-noise ratio (CNR) was calculated. The ratio of the ¹²³ I to ¹²⁴ I activity concentration was determined at which the contrast-to-noise ratio was equal for both modalities. This metric was defined as the contrast equivalent activity ratio (CEAR).

RESULTS

CEARs of 47.7, 25.6, 23.1, 14.6, 10.0, and 9.1 were obtained for a TOF and PSF modeled ¹²⁴ I reconstruction method and an attenuation and scatter-corrected ¹²³ I reconstruction method for sphere sizes of 10 to 37 mm, respectively. As the effective radiation dose of ¹²⁴ I-mIBG is higher than of ¹²³ I-mIBG (in mSv/MBq), an equal effective dose corresponds to a CEAR of 5 to 10. Therefore, CEARs higher than 5 to 10 indicate that ¹²⁴ I PET/CT outperforms ¹²³ I SPECT/CT in the sense of image quality for equal patient effective radiation dose.

CONCLUSION

The CEAR is much larger than a factor of 5 to 10 (needed for equal patient effective radiation dose) for most of the reconstruction methods and sphere sizes. Therefore, ¹²⁴ I-mIBG PET/CT is expected to improve image quality and/or may be used to reduce effective patient dose as compared with ¹²³ I-mIBG SPECT/CT.

Functional Imaging Signature of Patients Presenting with Polycythemia/Paraganglioma Syndromes

Pheochromocytoma/paraganglioma (PPGL) syndromes associated with polycythemia have previously been described in association with mutations in the von Hippel-Lindau gene. Recently, mutations in the prolyl hydroxylase gene (PHD) 1 and 2 and in the hypoxia-inducible factor 2 α (HIF2A) were also found to be associated with multiple and recurrent PPGL. Such patients also presented with PPGL and polycythemia, and later on, some presented with duodenal somatostatinoma. In additional patients presenting with PPGL and polycythemia, no further mutations have been discovered. Because the functional imaging signature of patients with PPGL-polycythemia syndromes is still unknown, and because these tumors (in most patients) are multiple, recurrent, and metastatic, the goal of our study was to assess the optimal imaging approach using 4 different PET radiopharmaceuticals and CT/MRI in these patients. Methods: Fourteen patients (10 women, 4 men) with confirmed PPGL and polycythemia prospectively underwent ⁶⁸Ga-DOTATATE (13 patients), ¹⁸F-FDG (13 patients), ¹⁸F-fluorodihydroxyphenylalanine (¹⁸F-FDOPA) (14 patients), ¹⁸F-fluorodopamine (¹⁸F-FDA) (11 patients), and CT/MRI (14 patients). Detection rates of PPGL lesions were compared between all imaging studies and stratified between the underlying mutations. Results:¹⁸F-FDOPA and ¹⁸F-FDA PET/CT showed similar combined lesion-based detection rates of 98.7% (95% confidence interval [CI], 92.7%-99.8%) and 98.3% (95% CI, 90.9%-99.7%), respectively. The detection rates for ⁶⁸Ga-DOTATATE (35.3%; 95% CI, 25.0%-47.2%), ¹⁸F-FDG (42.3; 95% CI, 29.9%-55.8%), and CT/MRI (60.3%; 95% CI, 48.8%-70.7%) were significantly lower (P < 0.01), irrespective of the mutation status. Conclusion:¹⁸F-FDOPA and ¹⁸F-FDA are superior to ¹⁸F-FDG, ⁶⁸Ga-DOTATATE, and CT/MRI and should be the radiopharmaceuticals of choice in this rare group of patients.

The role of 68Ga-DOTA-NOC PET/CT in evaluating neuroendocrine tumors: real-world experience from two large neuroendocrine tumor centers

OBJECTIVE

Our aim was to assess the role of Ga-DOTA-NOC PET/CT as a tool for the management of neuroendocrine tumors (NETs), evaluating the clinical impact on patients from two large NET centers in different geopolitical settings.

PATIENTS AND METHODS

This is a retrospective study of patients with NETs who underwent Ga-DOTA-NOC PET/CT at Royal Liverpool University Hospital (UK) and at Mount Lebanon Hospital (Lebanon). Indications for imaging and findings of the PET/CT along with demographic and clinical outcome data were recorded and evaluated.

RESULTS

Four hundred and forty-five patients fulfilled the inclusion criteria, with a median age at the time of diagnosis of 56 (range: 3-90) years; 248 (55.7%) patients were male.Ga-DOTA-NOC PET/CT was indicated for staging in 193 (43.4%) patients, for diagnosis in 124 (27.9%) patients, for follow-up in 97 (21.7%) patients, and for identification of a primary NET site in 31 (7%) patients.One hundred and four (27.9%) patients underwent Ga-DOTA-NOC PET/CT for the primary diagnosis of NET, of whom 66 (52.7%) patients presented with a clinical suspicion of NET, 10 (8.3%) patients presented with a biochemical suspicion of NET only, and 48 (38.8%) patients presented with a suspicious NET lesion discovered on another imaging modality. The most common clinical presentation was typical carcinoid syndrome [4 (33%) patients].Results on the basis of histology were used as the gold standard for the diagnosis in 57% of patients and the remaining on the basis of follow-up as per established clinical consensus. Sensitivity, specificity, negative-predictive value, and positive-predictive value of PET/CT were 87.1, 97.7, 79.6, and 98.7%, respectively, for the entire sample. Accuracy was measured using the receiver operating characteristic curve analysis with an area under the curve of 0.924 (95% confidence interval: 0.874-0.974).

CONCLUSION

Ga-DOTA-NOC PET/CT is a highly sensitive and specific study for the diagnosis and follow-up of patients with neuroendocrine tumors. These results support the use of Ga-DOTA-NOC PET/CT contributing significantly toward the clinical management of NET patients.

Management of Adrenal Masses

An adrenal mass can be either symptomatic or asymptomatic in the form of adrenal incidentalomas (AIs) in up to 8 % in autopsy and 4 % in imaging series. Once a diagnosis of adrenal mass is made, we need to differentiate whether it is functioning or nonfunctioning, benign, or malignant. In this article, we provide a literature review of the diagnostic workup including biochemical evaluation and imaging characteristics of the different pathologies. We also discuss the surgical strategies with laparoscopy as the mainstay with partial adrenalectomy in select cases and adrenalectomy in large masses. Follow-up protocol of AIs and adrenocortical carcinoma is also discussed.

Utility of FDG-PET imaging in screening for succinate dehydrogenase B and D mutation-related lesions

OBJECTIVE

Mutations of the genes encoding succinate dehydrogenase B and D (SDHB, SDHD) are associated with highly penetrant phenotypes, including paragangliomas and phaeochromocytomas. Patients with these mutations require lifelong surveillance; however, there is currently ambiguity regarding the optimal screening regimen. We sought to determine the utility of fluorodeoxyglucose (18F) positron emission tomography (18F-FDG PET) imaging, compared to other modalities for detecting SDHB and SDHD mutation-related lesions.

DESIGN

A retrospective audit of patients with SDHB or SDHD mutation.

PATIENTS

All adult patients with confirmed SDHB and SDHD mutations who underwent 18F-FDG PET/CT at our institution between 1 July 2011 and 30 May 2015.

MEASUREMENTS

18F-FDG PET/computed tomography (CT) performed during surveillance of patients with SDHB and SDHD mutations. Lesion numbers and locations detected by 18F-FDG PET were compared to those identified on the CT component, as well as other imaging modalities and histology when available.

RESULTS

Thirty-one 18F-FDG PET/CT studies were completed on 22 patients. For SDHB (20 patients), there were five positive and 21 negative studies. There were no false-negative 18F-FDG PET studies. Positive 18F-FDG PET findings correlated with magnetic resonance imaging (MRI), CT and [68 Ga]-DOTA(0)-Tyr(3)-octreotate (68 Ga DOTATATE PET/CT) imaging with no missed lesions; the only potential false-positive result relating to nonspecific postoperative changes (sensitivity 100·0%, specificity 95·5%). For SDHD (two patients), lesions were detected on 18F-FDG PET and correlated with other imaging in three of five studies. Metastatic lesions were incompletely visualized on 18F-FDG PET but were detected on the noncontrast fusion CT.

CONCLUSIONS

18F-FDG PET/CT is suitable for detecting SDHB and SDHD mutation-related lesions and may be considered effective for periodic surveillance of patients with these mutations.

Unusual Presentation of Bladder Paraganglioma: Comparison of (131)I MIBG SPECT/CT and (68)Ga DOTANOC PET/CT

Extraadrenal chromaffin cell-related tumors or paragangliomas are rare, especially in the bladder, accounting for less than 1% of cases. We report a 16-year-old boy who presented with hematuria and paroxysmal headache and was found to have a prostatic growth infiltrating the urinary bladder on anatomical imaging. Iodine-131 ((131)I) metaiodobenzylguanidine (MIBG) whole-body scanning and subsequently gallium-68 ((68)Ga) DOTANOC positron emission tomography/computed tomography (PET/CT) were performed. The MIBG scan revealed a non-tracer-avid soft-tissue mass, while DOTANOC PET/CT revealed a tracer-avid primary soft-tissue mass involving the urinary bladder and prostate with metastasis to the iliac lymph nodes. He underwent surgical management; histopathology of the surgical specimen revealed a bladder paraganglioma, whereas the prostate was found to be free of tumor.

A family with pheochromocytoma-paraganglioma inherited tumour syndrome. Serial 18F-DOPA PET/CT investigations

AIM

Hereditary pheochromocytoma-paraganglioma syndromes are characterized by multiple pheochromocytomas (PCC) and paragangliomas (PGLs), inherited in an autosomal dominant manner. Early detection and removal of tumours may prevent or minimize complications related to mass effects and malignant transformation. Having confirmed the diagnosis, it is important to localize the tumours and reveal their extent preoperatively. This study aimed to introduce 18F-DOPA PET/CT as a highly sensitive non-invasive diagnostic tool for early detection of mass lesions in patients with pheochromocytoma-paraganglioma inherited tumour syndrome and to report about its impact on patient management.

PATIENTS, METHODS

We are currently supervising one of the largest documented families in Germany with genetically determined SDHD gene mutation. We performed 18F-DOPA PET/CT in order to detect tumours in asymptomatic gene carriers and enable subsequent surgical therapy.

RESULTS

In seven patients undergoing 12 18F-DOPA PET/CT scans 17 lesions have been detected. Three of these lesions, located in the head and neck region, have had no morphologic correlate in CT and one had also no morphologic correlate in MRI. Of the six histologically analyzed lesions five have been tumors (PGL or PCC) and one has been a nodular hyperplasia. This means the 18F-DOPA PET/CT scan in our study group had a sensitivity of 83%. 18F-DOPA PET/CT investigations lead to change in the management in 5/7 studied patients (70%).

CONCLUSION

The benefits of PET/CT in detection of pheochromocytoma and paraganglioma are well documented, but we are the first to use this technique for screening of a rare hereditary disease (estimated prevalence 0.3/100 000).

5th International ACC Symposium: Imaging for Diagnosis and Surveillance of Adrenal Tumors--New Advances and Reviews of Old Concepts

Adrenocortical carcinoma (ACC) is often diagnosed incidentally. However, significant difficulties persist in diagnosing the rare ACC among the very common benign adrenal tumors, which are present in up to 5% of the population. Due to the very low prevalence of ACC, prospective studies are impossible to conduct. Two recent studies took the approach of reviewing preexisting adrenal tumors prior to the diagnosis of ACC. These data challenge current concepts of diagnosis and surveillance of incidentally discovered masses. Oncocytomas (benign and malignant) represent an entity that can be difficult to be diagnosed by radiographic characteristics and even histologically. However, some recent data provides insight into their appearance in imaging procedures. With regards to ACC specific imaging, which could be applied for differential diagnosis of adrenal tumors, surgery planning and surveillance several radionucleotides have been evaluated over the last decades showing promising results. Of particular interest, these substances can potentially be used for therapy as well.

Adrenal Imaging and Intervention

The adrenal glands are a common site for primary benign and malignant tumors and metastatic disease. Computed tomography (CT), MR imaging, and fluorine-18 fluorodeoxyglucose PET combined with CT are the most common imaging modalities used to assess the adrenal glands. There are established morphologic criteria for both CT and MR imaging that can be used to assess whether an adrenal mass is benign or malignant, and whether follow-up, biopsy, or resection should be performed. In the setting of a known primary malignancy, CT, MR imaging, and PET can help differentiate most benign masses from metastasis.

Images of pheochromocytoma in adrenal glands

Pheochromocytomas are relatively rare tumors of the adrenal medulla. A wide spectrum of imaging findings has been described. The aim of this article is to describe the multimodality imaging features of pheochromocytomas including diagnostic pearls that can help differentiate them from other adrenal lesions and pitfalls to avoid.

Metabolic and anatomic characteristics of benign and malignant adrenal masses on positron emission tomography/computed tomography: a review of literature

PET/CT with (18)F-fluorodeoxyglucose (FDG) or using different radiocompounds has proven accuracy for detection of adrenal metastases in patients undergoing cancer staging. It can assist the diagnostic work-up in oncology patients by identifying distant metastases to the adrenal(s) and defining oligometastatic disease that may benefit from targeted intervention. In patients with incidentally discovered adrenal nodules, so-called adrenal "incidentaloma" FDG PET/CT is emerging as a useful test to distinguish benign from malignant etiology. Current published evidence suggests a role for FDG PET/CT in assessing the malignant potential of an adrenal lesion that has been 'indeterminately' categorized with unenhanced CT, adrenal protocol contrast-enhanced CT, or chemical-shift MRI. FDG PET/CT could be used to stratify patients with higher risk of malignancy for surgical intervention, while recommending surveillance for adrenal masses with low malignant potential. There are caveats for interpretation of the metabolic activity of an adrenal nodule on PET/CT that may lead to false-positive and false-negative interpretation. Adrenal lesions represent a wide spectrum of etiologies, and the typical appearances on PET/CT are still being described, therefore our goal was to summarize the current diagnostic strategies for evaluation of adrenal lesions and present metabolic and anatomic appearances of common and uncommon adrenal lesions. In spite of the emerging role of PET/CT to differentiate benign from malignant adrenal mass, especially in difficult cases, it should be emphasized that PET/CT is not needed for most patients and that many diagnostic problems can be resolved by CT and/or MR imaging.

FDG-PET/CT and FLT-PET/CT for differentiating between lipid-poor benign and malignant adrenal tumours

OBJECTIVE

To compare F-18-fluorodeoxyglucose (FDG) and F-18-fluorothymidine (FLT) PET/CT examinations for differentiating between benign and malignant adrenal tumours.

METHODS

Thirty lipid-poor benign and 11 malignant tumours of 40 patients were included. FDG- and FLT-based indices including visual score, maximum standardized uptake value (SUVmax) and FDG adrenal lesion/liver SUVmax (A/L SUVmax) or FLT adrenal lesion/back muscle SUVmax (A/B SUVmax) ratio were compared between benign and malignant tumours using the Mann-Whitney's U or Wilcoxon signed-rank test, and their diagnostic performances were evaluated by means of the area under the curve (AUC) values derived from the receiver operating characteristic analysis.

RESULTS

All indices were significantly higher in malignant than benign tumours on both images (p < 0.05 each). On FDG-PET/CT, the sensitivity, specificity, and accuracy were 91 %, 63 % and 71 % for visual score, 91 %, 67 % and 73 % for SUVmax, and 100 %, 70 % and 78 % for A/L SUVmax ratio, respectively. On FLT-PET/CT, they were 100 %, 97 % and 98 % for visual score, SUVmax and A/B SUVmax ratio, respectively. All FLT indices were significantly higher than those of FDG in AUC (p < 0.05 each).

CONCLUSION

FLT-PET/CT may be superior to FDG-PET/CT in differentiating lipid-poor benign from malignant adrenal tumours because of higher specificity and accuracy.

KEY POINTS

• All FDG indices were significantly higher in malignant than in benign tumours. • All FLT indices were significantly higher in malignant than in benign tumours. • All FLT indices were significantly higher than those of FDG in AUC.

From the radiologic pathology archives: Adrenal tumors and tumor-like conditions in the adult: radiologic-pathologic correlation

Advanced imaging often reveals adrenal tumors and tumor-like conditions in both symptomatic and asymptomatic patients. When adrenal disease is clinically suspected, cross-sectional imaging can be helpful in evaluating the etiology of the patient's symptoms. When adrenal disease is incidentally identified, what the clinician and patient really want to know is whether the findings are benign or malignant, as this ultimately will affect their next step in management. Using radiologic-pathologic correlation, we broadly classify common, uncommon, and rare tumors and tumor-like conditions that can occur in the adrenal as benign or malignant. This classification follows predominant trends in observed biologic behavior while acknowledging those tumors that may behave in the minority in an unpredictable manner. We review the clinical background and presentation of functional adrenal tumors including Conn syndrome, Cushing syndrome, and catecholamine-secreting tumors, as well as their relationship with adrenal anatomy. We discuss a variety of benign tumors, including adrenal cortical adenoma (including oncocytoma) and pheochromocytoma, as well as uncommonly and rarely encountered tumors such as myelolipoma, hemangioma, lymphangioma, schwannoma, ganglioneuroma, and adenomatoid tumor. A variety of tumefactive but nonneoplastic lesions are addressed, including adrenal cortical hyperplasia, adrenal hemorrhage, adrenal cysts, and infections. Malignant tumors discussed include adrenal cortical carcinoma, the rare malignant pheochromocytoma, lymphoma, metastases, and sarcomas. For each tumor and tumor-like lesion, the clinical presentation, epidemiology, key imaging findings, diagnostic differential considerations, and management options are briefly addressed. Finally, an approach to the workup of suspected or incidentally discovered tumors is presented based on a selected literature survey and our clinical experience. Radiologists play an important role in identification and diagnosis of adrenal tumors and tumor-like conditions in both symptomatic and asymptomatic patients.

Update on the optimal management of patients with vascular extension of pheochromocytoma

AIM

Vascular extension of pheochromocytoma is extremely rare but highly resectable. The aim of this study was to review the available information in the literature for patients with this condition.

METHODS

A systematic literature search produced individual data for 29 treated patients with vascular extension of pheochromocytoma mainly to the inferior vena cava.

RESULTS

Out of 29 reported cases, 26 have been treated surgically. Nine of these patients required cardiopulmonary bypass. Two patients died untreated and one patient declined surgical treatment and discharged to follow-up. In 24 patients including nine with primarily missed diagnosis, surgery was documented as curative.

CONCLUSION

Surgeons need to be aware of this extremely rare characteristic feature of pheochromocytoma and indicated medical work-up in order to properly diagnose and manage this challenging group of patients.

Pheochromocytoma and paraganglioma: an endocrine society clinical practice guideline

OBJECTIVE

The aim was to formulate clinical practice guidelines for pheochromocytoma and paraganglioma (PPGL).

PARTICIPANTS

The Task Force included a chair selected by the Endocrine Society Clinical Guidelines Subcommittee (CGS), seven experts in the field, and a methodologist. The authors received no corporate funding or remuneration.

EVIDENCE

This evidence-based guideline was developed using the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) system to describe both the strength of recommendations and the quality of evidence. The Task Force reviewed primary evidence and commissioned two additional systematic reviews.

CONSENSUS PROCESS

One group meeting, several conference calls, and e-mail communications enabled consensus. Committees and members of the Endocrine Society, European Society of Endocrinology, and Americal Association for Clinical Chemistry reviewed drafts of the guidelines.

CONCLUSIONS

The Task Force recommends that initial biochemical testing for PPGLs should include measurements of plasma free or urinary fractionated metanephrines. Consideration should be given to preanalytical factors leading to false-positive or false-negative results. All positive results require follow-up. Computed tomography is suggested for initial imaging, but magnetic resonance is a better option in patients with metastatic disease or when radiation exposure must be limited. (123)I-metaiodobenzylguanidine scintigraphy is a useful imaging modality for metastatic PPGLs. We recommend consideration of genetic testing in all patients, with testing by accredited laboratories. Patients with paraganglioma should be tested for SDHx mutations, and those with metastatic disease for SDHB mutations. All patients with functional PPGLs should undergo preoperative blockade to prevent perioperative complications. Preparation should include a high-sodium diet and fluid intake to prevent postoperative hypotension. We recommend minimally invasive adrenalectomy for most pheochromocytomas with open resection for most paragangliomas. Partial adrenalectomy is an option for selected patients. Lifelong follow-up is suggested to detect recurrent or metastatic disease. We suggest personalized management with evaluation and treatment by multidisciplinary teams with appropriate expertise to ensure favorable outcomes.

Differential diagnosis of adrenal mass using imaging modality: special emphasis on f-18 fluoro-2-deoxy-d-glucose positron emission tomography/computed tomography

Adrenal incidentalomas are adrenal masses serendipitously detected during an imaging study performed for reasons unrelated to suspicion of adrenal disease. The incidence of adrenal incidentalomas has increased because of the widespread use of various imaging modalities. In oncology patients with adrenal incidentalomas, the characterization of the adrenal masses is challenging because nearly 50% of incidental adrenal masses are metastatic lesions that need special medical attention. Although unenhanced computed tomography (CT) densitometry, chemical shift magnetic resonance imaging (MRI), delayed contrast-enhanced CT and CT histogram analysis have been used as sensitive and specific modalities for differentiating benign from malignant adrenal masses, F-18 fluoro-2-deoxy-D-glucose positron emission tomography (F-18 FDG PET)/CT is a highly accurate imaging modality compared to CT or MRI, especially when these two imaging modalities are combined. In addition, a semiquantitative analysis using standardized uptake value ratio further improves the diagnostic accuracy of F-18 FDG PET/CT in differentiating benign from malignant adrenal masses. Thus, F-18 FDG PET/CT is very helpful for determining the best therapeutic management, especially for assessing the need for surgery.

(11)C-hydroxyephedrine positron emission tomography in the postoperative management of pheochromocytoma and paraganglioma

AIM

Accurate detection of recurrent disease and restaging are essential in the postoperative surveillance of many patients with pheochromocytomas (PHEOs) and paragangliomas (PGLs). In this study, the impact of positron emission tomography (PET) and PET/computed tomography (CT) with (11)C-hydroxyephedrine (HED) was evaluated for the postoperative surveillance and diagnosis of recurrent disease and for functional monitoring of locoregional and systemic therapy.

METHODS

One hundred and eleven HED-PET and PET/CT examinations performed in 48 patients after surgical intervention for PHEO/PGL were analyzed retrospectively. In a subgroup of 16 patients who underwent systemic and locoregional therapies, the tracer uptake in tumors was also measured as the functional volume (FV), maximum standardized uptake value (SUVmax), mean SUV (SUVmean) and as the total catecholamine transporter tumor volume (TCTTV) calculated as TCTTV = FV × SUVmean. The PET imaging results were correlated with CT/magnetic resonance imaging findings and biochemical and clinical follow-up data.

RESULTS

In the first postoperative examination, HED-PET was positive in 24/48 and negative in 24/48 patients with no false-positive results, yielding 92.3% sensitivity and 100% specificity. For the 16 patients, there was a significant correlation between FV and SUVmax and SUVmax and TCTTV. TCTTV correlated significantly with plasma and urinary catecholamines. In 11/16 patients, SUVmax and TCTTV increased/decreased in parallel but not in the remaining 5 patients.

CONCLUSION

HED-PET and PET/CT were found to be valuable in the postoperative follow-up in detecting recurrent and metastatic disease. In a subgroup of patients, functional monitoring of systemic and locoregional therapies was feasible by assessing the changes of the TCTTV, and therefore warrants further prospective evaluation.